// MIT License
// 开源地址：https://gitee.com/co1024/AbcMvc
// Copyright (c) 2021-2023 1024
// Abc.Mvc=Furion+EF+SqlSugar+Pear layui admin.

using System.Diagnostics;
using System.Text.RegularExpressions;

namespace Abc.Utils;

/// <summary> 载入资源中的动态链接库(dll)文件
/// </summary>
public static class AssemblyHelper
{
    /// <summary> 已加载DLL
    /// </summary>
    private static Dictionary<string, Assembly> LoadedDlls = new();

    /// <summary> 已处理程序集
    /// </summary>
    private static readonly Dictionary<string, object> Assemblies = new();

    /// <summary> 在对程序集解释失败时触发
    /// </summary>
    /// <param name="sender">AppDomain</param>
    /// <param name="args">事件参数</param>
    private static Assembly AssemblyResolve(object sender, ResolveEventArgs args)
    {
        //程序集
        //获取加载失败的程序集的全名
        var assName = new AssemblyName(args.Name).FullName;
        //判断Dlls集合中是否有已加载的同名程序集
        if (LoadedDlls.TryGetValue(assName, out var ass) && ass != null)
        {
            LoadedDlls[assName] = null;//如果有则置空并返回
            return ass;
        }
        else
        {
            throw new DllNotFoundException(assName);//否则抛出加载失败的异常
        }
    }

    /// <summary> 注册资源中的dll
    /// </summary>
    /// <param name="pattern">*表示连续的未知字符,_表示单个未知字符,如*.dll</param>
    public static void RegistDLL(string pattern = "*.dll")
    {
        System.IO.Directory.GetFiles("", "");
        //获取调用者的程序集
        var ass = new StackTrace(0).GetFrame(1).GetMethod().Module.Assembly;
        //判断程序集是否已经处理
        if (Assemblies.ContainsKey(ass.FullName))
        {
            return;
        }
        //程序集加入已处理集合
        Assemblies.Add(ass.FullName, null);
        //绑定程序集加载失败事件(这里我测试了,就算重复绑也是没关系的)
        AppDomain.CurrentDomain.AssemblyResolve += AssemblyResolve;
        //获取所有资源文件文件名
        var res = ass.GetManifestResourceNames();
        var regex = new Regex("^" + pattern.Replace(".", "\\.").Replace("*", ".*").Replace("_", ".") + "$", RegexOptions.IgnoreCase);
        foreach (var r in res)
        {
            //如果是dll,则加载
            if (regex.IsMatch(r))
            {
                try
                {
                    var s = ass.GetManifestResourceStream(r);
                    var bts = new byte[s.Length];
                    s.Read(bts, 0, (int)s.Length);
                    var da = Assembly.Load(bts);
                    //判断是否已经加载
                    if (LoadedDlls.ContainsKey(da.FullName))
                    {
                        continue;
                    }
                    LoadedDlls[da.FullName] = da;
                }
                catch
                {
                    //加载失败就算了...
                }
            }
        }
    }
}